1. Field of the Invention
This invention relates to a switchboard or display board for electrical monitoring and control systems, comprising two or more sub-assemblies distributed over the board and each of which comprises a display or control device, or the like, visible on a visible side of the board, particularly switching keys and keyboards.
2. Description of the Prior Art
In the previous practice, such boards comprise a body, which in most cases consists of a sheet metal carrier plate in a carrying frame, and the sheet metal plate is formed with window openings for each display field and for switching and setting means, which are operable from the visible side of the board, whereas additional sub-assemblies, which need not be directly accessible from the visible side, are mounted in covered regions. It is also known to use a larger panel composed of a plurality of fields, which extend over the width of the panel and are held in the frame and each of which receives one or more sub-assemblies and is provided with the necessary apertures and windows. It is finally also known to mount display screens and display means with associated switching and setting means, particularly switching keys and keyboards, on plates which have corresponding display and/or actuating openings and to insert these plates into corresponding apertures of the panel unless the size of the plate and panel incidentally correspond to each other in at least one dimension. Besides, it is often necessary to mount keyboards, switches and actuating means which are associated with existing display means or display screens in a manner prescribed or desired by the customer for functional or aesthetic reasons, and it may be necessary in each such case to provide identical elements in different groupings and with different labels and/or designations. For all these reasons, the manufacture and assembling of switch and display boards of the kind mentioned first hereinbefore and the manufacture of display devices and display screens with associated switching and control means in a certain arrangement has previously constituted a considerable problem and the space existing on a switch or display board cannot efficiently be utilized and all boards which are not absolutely identical must be individually manufactured from separate elements and with separate apertures at least as far as the visible side of the panels is concerned. An extension or alteration of the arrangement of the sub-assemblies will often be possible only if the panel is entirely disassembled and a new front plate with corresponding apertures is employed.